Add some minor stylistic aspects

Author: biboudis

docs/docs/contributing/backend.md

@@ -4,8 +4,11 @@ title: Working with the Backend
 ---
 
 The compiler backend is based on a fork of the Scala 2.11 `GenBCode` backend and
-lives at https://github.com/lampepfl/scala/tree/sharing-backend. The dotty
-source tree contains a git submodule in the directory
+lives at 
+
+> https://github.com/lampepfl/scala/tree/sharing-backend. 
+
+The dotty source tree contains a git submodule in the directory
 [scala-backend](https://github.com/lampepfl/dotty/tree/master/scala-backend)
 that points to this fork. We do not compile every file in this submodule,
 instead we add the subset of files we need to the dotty-compiler project in the
@@ -16,39 +19,44 @@ their content is not automatically updated when you do `git checkout` or `git
 pull`, instead everytime you switch branch, you need to do:
 
 ``` shell
-git submodule update --init
+$ git submodule update --init
 ```
 
 ## Environment setup
 
-1. Set the following git configuration options to make working with submodules
-easier, see the [Git Book](https://git-scm.com/book/en/v2/Git-Tools-Submodules)
+1. Set the following git configuration options to make working with submodules easier, 
+see the [Git Book](https://git-scm.com/book/en/v2/Git-Tools-Submodules)
 for more information:
 ``` shell
-git config --global diff.submodule log
-git config --global status.submodulesummary 1
-git config --global push.recurseSubmodules check
+$ git config --global diff.submodule log
+$ git config --global status.submodulesummary 1
+$ git config --global push.recurseSubmodules check
 ```
 
-2. Fork https://github.com/lampepfl/scala (in the following commands,
-   `dotty-staging/scala` is used as a placeholder for your
-   own fork).
-3. ```shell
-   cd scala-backend
-   git remote add scala-staging git@github.com:dotty-staging/scala.git
-   cd ..
-   ```
+2. Fork scala from github
+
+> https://github.com/lampepfl/scala 
+
+(in the following commands, `dotty-staging/scala` is used as a placeholder for your own fork).
+
+3. Add the new remote to track the upstream branch
+```shell
+$ cd scala-backend
+$ git remote add scala-staging git@github.com:dotty-staging/scala.git
+$ cd ..
+```
 
 ## Workflow when changing to the backend
 
 ```shell
-cd scala-backend
-git checkout -b my-feature-branch
+$ cd scala-backend
+$ git checkout -b my-feature-branch
+
 # Make some changes ...
+$ git push -u scala-backend
 
-git push -u scala-backend
 # Open a PR against https://github.com/lampepfl/scala/tree/sharing-backend
-cd ..
+$ cd ..
 ```
 
 Once your PR has been merged into the backend, you'll need to make another PR